The invention is based on a device for injecting fuel in combustion chambers as defined hereinafter. In a known device of this type (German Pat. No. 834 467), the heating coil of a glow plug surrounds the fuel spray emerging from an injection nozzle. Additionally, fresh air is blown out of the cylinder asymmetrically and laterally at right angles to the injected spray at one point in the injection conduit. In this apparatus, although portions of the fuel which had previously been heated are transported into the cylinder in an accelerated manner, the disadvantage nevertheless exists that parts of the fuel strike the heating coil of the glow plug and partially carbonize there, and further that fuel particles are blown against the wall of the injection conduit by the fresh air stream emerging from the side. Optimal combustion does not take place, which has an unfavorable effect on both efficiency and exhaust gas composition.